Failed IUI, weird AF after

I apologize in advance if this is not the appropriate place to be asking this, but I tried searching a variety of ways and I'm hoping to get a better answer here.

On Wednesday 4/04, I came to terms with the fact that our recent IUI failed when I still got a negative on HPT on CD 28.  My cycle is usually like clockwork, so this would be the expected day to start.  They had told me in advance to stop taking the progesterone suppositories so that my period would start if the HPT wasn't positive.  I had taken the last one on Tuesday night.  AF arrived Friday morning.  I was not told to expect anything different with AF after coming off the Progesterone, and I'm thinking maybe this is typical, but I'm unsure.  On Friday, I was having some intense cramps.  I'm quite lucky in the fact that during most cycles, I don't really cramp much.  When I do cramp, it's usually not for too long (maybe a few hours off and on).  Anyway, something just felt weird and when I went to the bathroom there was a large clot with gray looking tissue (like the size of a quarter I guess), which completely freaked me out.  Maybe 15 minutes later, I went again and had another one of almost identical size/appearance.  This is not normal for me at all.  I've been consistently passing clots ever since, but smaller, from dime to pea sized maybe.  Plus, I'm still experiencing cramping, bloating and gas.  I'm assuming it's an after effect of stopping the progesterone.  I'm just concerned at the fact that there's so many clots as opposed to an actual flow.  Has anyone had a similar experience?

Thanks.